Well drilling indicating apparatus



oooooo IN V EN TORS. ZZ/Pifiizer Jr, 7 Wm 3 Sheets-Sheet 1 T James I T W\\ J W PITCHER EI'AL WELL DRILLING INDICATING APPARATUS Dec. 30, 1952 Filed June 13, 1945 .3 Sheets-Sheet 2 INVEN TORS. @fizm e5 ZflPziicker:

Dec. 30, 1952 J w PITCHER ETAL WELL DRILLING INDICATING APPARATUS Filed June 13, 1945 Dec. 30, 1952 .1. w. PITCHER ETAL WELL DRILLING INDICATING APPARATUS 3Sheets-Sheet 3 Filed June 15, 1945 INVENTORS. James ZUPLZZ/zer L/Zhn m M )WWA/ fi Patented Dec. 30, 1952 WELL DRILLING INDICATING APPARATUS James W. Pitcher and John T. ilallahan, Jr.,

Tulsa, Okla., assignors to Engineering Laboratories, 1110., Tulsa, Okla., a corporation of Oklahoma Application June 13, 1945, Serial No. 599,134

4 Claims.

The present invention relates to improved apparatus for indicating the rate of drilling a well, the depth of the well, and the position of the drill string relative to the well bottom during off-bottom movement of the drill string, and more particularly to improvements in apparatus of the general character described in Patent No. 2,326,219-Hayward and Patent No. 2,166,212 -Hayward.

As explained in the above noted Hayward patent of higher number, in modern well drilling operations utilizing rotary rigs, it is highly important that the progress of the drill at the end of the drill string and the depth of the well be known at all times within very narrow limits of accuracy, in order that the tests and indications which are representative of particular strata may be correctly related to the actual depth of the strata in the well. It is also important during off-bottom movements of the drill string, which are required in raising and lowering the drill string for pipe joint additions and bit changing purposes, to know the exact position of the drill string relative to the bottom of the well, since otherwise caution requiring the consumption of time must be exercised in lowering the drill string until the bit end thereof reaches the well bottom. In the interests of ease-of operation, a system for providing the described indications should also include facilities for so correlating the functions of the indicating devices that they are automatically rendered operative only during appropriate movements of the drill string without any intervention on the part of the equipment user. Thus, for example, the oil-bottom drill string indicating facilities should remain inactive dur ing a drilling period when the depth and drilling rate indicating facilities are in operation. Con versely the well depth and drilling rate indi-= eating devices should be rendered inactive without changing the settings thereof incident to off-bottom movement of the drill string.

It is an object of the present invention, therefore, to provide simple, rugged and reliably accurate apparatus of low cost for concurrently indicating the depth of a well and the rate of drilling, and for indicating the position of the drill string relative to the bottom of the well during off-bottom movement of the drill string.

. 2 string position indicating device that these devices are only rendered operative during corresponding drilling or non-drilling intervals, all with a minimum duplication of equipment.

It is a further object of the invention to provide improved drilling rate indicating apparatus which is of rugged and economical construction, may be easily installed, operated and serviced by relatively unskilled users of the apparatus, and is reliably accurate in its operation to provide an indication of the rate of progress of a drill string into a well.

It is still another object of the inventionto provide improved and simplified apparatus for indicating the depth of a well and an indication of off-bottom movement of the drill string.

The invention, both asto its organization and method of operation, together with further objects and advantages thereof, will best be understood by reference to the following specification taken in connection with the accompanying drawings, in which:

Figs. 1 and 2, when positioned one above the other in the order named, schematically illustrate improved apparatus characterized by the features of the present invention;

Fig. 3 is a front view of the indicating devices and associated mechanism shown in Fig. 1 of the drawings;

Fig. 4 is a detail view partially in section taken along the lines 4-4 in Fig. 3;

Fig.5 is a'- detail view of the pulse generating cams and contact assemblies included in the apparatus shown in Fig. 1;

Fig. 6 is a detail view illustrating certain components of the apparatus shown in Fig. 2;

Fig. '7 is a detailed view of the differential mechanism embodied in the apparatus shown in Fig. 1;

Fig. 8 is an enlarged fragmentary view of the clutch mechanism embodied in the apparatus shown in Fig. 1; and

Fig. 9 is a schematic view of the indicating facilities associated with the apparatus shown in Fig. 2.

Referring now to the drawings and more particularly to Figs. 1 and 2 thereof, the present improved apparatus is there illustrated in its use to indicate, during a well drilling operation. the rate of penetration of a drill bit l2 into a well ill, the depth of the well, and the position of the drill string ll relative to the well during .ofi-bottom movement of the string. Specifically, the bit I2 is carried at the lower end of a string of hollow drill pipe H of the character ordinarily employed in a rotary drilling operation. This bit is provided with drilling fluid openings l3 through which drilling fluid or mud of the type conventionally used in rotary drilling operations is discharged into the drill hole at the bottom thereof for upward movement to the top of the well through the annular space between the drill string and the side walls of the well. At its upper end, the drill string II is carried by the usual Kelly Ha which is attached by means of a swivel I4 to the hook of a travelling block IS. A hoisting or drilling line H; connecting the travelling block I! with the usual crown pulley 6 provided at the top of the derrick I. is utilized to raise and lower the drill string relative to the bottom of the well iii. A rotary table 9 of conventional construction and supported by the derrick floor 6 is utilized to impart rotary movement to the Kelly and drill string during each drilling period.

All of the described indications are obtained by measuring the extent and rate of movement of the drill string ll relative to the top of the rotary table 9, whichsurface is utilized as the reference level. To this end, a measuring line I! is attached to the traveling block [6 and carried over two idler pulleys I8 and I9 supported at the underside of the derrick crown. Intermediate these pulleys, the measuring line is looped around a takeoff pulley 68 to rotate the latter pulley in accordance with movement of the drill string relative to the derrick platform 8. The free end of the measuring line I1 is passed through a tension demultiplying mechanism 20 of conventional structure to carry a tensioning weight 2|. Specifically, a weight 2i of approximately 200 pounds is used, and the tension demultiplication obtained within the mechanism 20 is such as to produce a tension of 12 pounds in the portion of the measuring line l1 which extends between the mechanism 26 and the travelling block [5. This measuring line is preferably constructed of metal, such, for example, as piano wire, having high tensile strength and a relatively low temperature-expansion characteristic. In this regard it is noted that the tension developed within the measuring line IT by the weight 2| should be such that no slippage occurs between this line and the takeoff pulley 60. The pulley 60 is connected through a shaft 6| to a drive sprocket 6 la, which in turn is utilized directly to actuate the improved well depth and off-bottom position indicating facilities illustrated in Fig. 1 of the drawings.

In brief, these facilities comprise well depth indicating means in the form of a plural order wheel register 65, off-bottom indicating means in the form of a second plural order wheel register 66, and a differential mechanism, indicated generally at 61, for selectively transmitting rotary movement of the drive sprocket 6Ia to the actuating shafts-of the two registers in a manner determined by the position of the drill bit l2 relative to the bottom of the well and the direction of movement of the drill string. The registers 65 and 66 are conventional revolution counters being respectively utilized to count the revolutions of the drive shafts 69 and 10 through which they are actuated. While these registers may be of any desired commercial construction, they are preferably of the type known as the Productimeter," Model -BA-711-C, manufactured by The Durant Manufacturing Company of Milwaukee, Wisconsin. Each register is capable of being reversely operated to add to v teeth of the two identified sprockets.

its total or to subtract fromthe amount registered therein, the order wheels being operated upon the decimal system with suitable tens transfer mechanisms being provided between the wheels of successively higher order. Further, the mechanism of each counter is such that when the actuating shaft thereof is rotated in the subtracting direction through the zero total setting thereof, all of the order wheels, and particularly the fourth order wheel III of the counter 66, tend to be rotated simultaneously to the 9 positions thereof.

More specifically considered and as best shown in Fig. '7 of the drawings, the differential mechanism 61 comprises an input or drive shaft 68 carrying a bevel gear 64 which meshes with a ring gear 96 rotatable about the shaft 69. This ring gear carries a differential yoke Hill, the legs of which are utilized rotatably to support the two orbital gears IIH and I02 of the mechanism. The latter gears in turn mesh with correspondingly beveled take-off gears I03 and I04 fixedly carried by the register drive shafts 69 and 10. In accordance with a particular feature of the present invention, the ring gear 86 is also utilized to drive a vernier disc 91 through the meshing bevel gear 95 and a shaft ll upon which the disc is mounted. This disc is provided with a scale around its peripheral edge graduated in fractions of a foot, and is arranged to coast with a stationary pointer 86 to provide fractional footage indications not registerable upon the register 66. In accordance with a further feature of the present invention, this plate is also provided with an axially offset manually operable knob 96 by means of which the shaft H may be rotated for the purpose of manually actuating either of the two registers 65 and 66 to any desired setting,

Rotation-of the differential drive shaft 68 in response to rotation of the drive sprocket Sla is obtained by providing a driving connection between these two elements which comprises an electro-magnetically operated clutch mechanism 15, an input shaft 64, and a chain and sprocket connection between the shaft 64 and the shaft 6|. This chain and sprocket connection comprises the sprccket 6la carried by the shaft 6|, a sprocket 63 mounted for rotation with the shaft 64, and an endless chain 62 engaging the The clutch mechanism I5 comprises a pair of clutch plates 12 and 13 respectively mounted upon the shafts 64 and 68 for rotation therewith, and normally held \in driving engagement by means of a coil spring 11 embracing the shaft 64 and stressed between the shaft bearing I8 and the plate 13. For the purpose of moving the shaft 64 axially to disengage the clutch plate 12 from the clutch plate 13, a declutching assembly is provided which comprises a clutch collar 14 rotatably carried by the shaft 64; an L-shaped arm 15a pivotally mounted as indicated at 8|; and having a bifurcated leg embracing the collar 14; and an in order to transmit rotary movement fro on-oif switch 33 which normally occupies its open circuit position. Y I

As will be evident from the above expla atlon,

best shown in Fig. 4 of the drawings, the-fourth order wheel III of the off-bottom register is drilled and tapped to receive a combination stop and switch actuating pin H which projects through an aperture of slightly greater diameter formed in the top wall of the register housing. With this arrangement. and when the order wheels of the register 36 all occupy their zero settings, rotation of the shaft 63 in the proper direction to drive the register 65 in its adding direction,tends to drive the shaft ill in its subtracting directiomi. e. to rotate the order wheels of the register 63 to their respective f'9" positions. 'Such tendency to rotate the shaft III is, however, prevented by engagement of the pin ii 0 with the edge of the housing aperture through which it extends, Thus. the pin 0 coacts with the register housing to lock the shaft against rotation during rotation of the shaft 68 in a di rection indicating an increase in the depth of the well It. 1

This pin is also utilized to so control the setting of a microswitch I05, of the single pole, double throw type, that the register 65 and shaft v 69 are locked against operation during elf-bottom movements of the drill string H. In this regard, it will be understood that in order to drive the register drive shaft 10 during off-bottom movement of thedrill string Ii, it is necessary to lock the shaft 69 against rotation. To this end the pin H0 is arranged for a small amount of movement within the housing aperture through which it extends, and is also arranged to coact with an arm I01 pivotally supported at I08 upon the housing of the register 66 to control the setting of the microswitch I05. Specifically, the arm it! is provided with an adjustable actuating screw I03 axially aligned with the microswitch actuating'button I06 and normally held in engagement with this button to hold the contacts H2 closed and the contacts H3 open under the influence of the force exerted upon the arm IN by the, pin H0 when the order wheels 66 occupy their zero setting and the shaft 68 is being driven in a direction to produce subtractive rotation of the shaft III. This force is,

of course, relieved in response to reverse rotation arm 3|, is utilized to lock the depth indicating register 65 against operation during off-bottom movement of the drillstring II.

The microswitch- I05, as controlled in the described manner by the off-bottom register 66, is also utilized to control the operation of the drilling rate indicating device illustrated in Fig. 2 of the drawings and is connected thereto by a conductor I20. This device is further controlled in accordance with the operation of the depth indicating register 65. To this end, the input shaft 43 carries for rotation therewith a gear 33 which is employed to drive a shaft 33 upon which twopulse generating cams 31 and 83 are mounted. The shaft 33 is iournalled for rotation in bearing members "carried by the housing of the register 33, and mounts a gear 84 meshing with the drive gear 33 and with which the latching element 9| is directly engageable. As best shown in Fig. 5

of the drawings, the pulse generating cams 81 and 38 are arranged respectively to control pulsing contacts 33 and 33 which are intermittently. closed through engagement by the cam lobes 31a and 33a. Assuming that the cams are rotated in a counter clockwise direction as viewed 1 from the left end of the shaft 85, the lobe 38a is disposed to lead the lobe 81a so that the contacts 30 are closed and then opened before closure of the contacts 33. With this arrangement, the two cam and pulsing contact assemblies function to generate two trains of pulses at a pulsing rate which is determined by the speed of rotation of the shaft 83. and hence variesin accordance with the rate of bit penetration into the well ill. The contacts 39 and 30 are connected by conductors l2! and I22 respectively with motors 28 and 52 described ingreater detail vhereinafter. pulsing rate for a given rate of bit movement may, of course. be changed as desired by appropriately changing the gear ratio between the shaft 69 and the cam shaft 85.

In brief, the drilling rate indicating device as shown in Fig. 2 of the drawings comprises an I tration of the bit i2 a given distance into the well l0, driving means including a constant and slow speed motor 28 are provided for moving the element 23 away from its normal setting. More specifically, thev motor 28 is normally connected in driving relationship with the element 23 through a driving connection which comprises a gear traimnot shown, a shaft 3!, and a pair of engaged clutch members 32 and 33, the first of which is mounted for rotation with shaft 3|, and the second of which is mounted for rotation with the shaft 24. The shaft 24 is journalled for rotary and axial movement in a bearing member 33 which is carried by the frame member 34a. This bearing member is provided with an enlarged cup-shaped part 38a which houses a hellcal restoring spring 39 having the function of normally biasing the shaft 24 and the element 23 to their respective normal settings, 1. e. to positions wherein the stop arm 25 engages the stop 26. The motor 28, gear train, shaft 3i and clutch member 32 are supported upon a second upstanding frame member 34b, suitable bearing means being provided upon this frame member for receiving the shaft 3|. For the purpose of normally maintaining the two clutch members 32 and 33in clutching engagement, a compression spring 31 is provided which is held under compression between the end of the bearing member 38 and the clutch member 33. To provide for intermittent declutching of the two clutch members, a clutch release mechanism is provided which comprises a clutch collar 35 mounted upon the shaft 24 and movable axially and rotatabiy relative thereto. This collar is interposed between the pinned to the shaft 24 and against which the A ball bearing assem- 7 spring 31 directly bears. bly 35b is interposed between the left end of t e spring 31' and the thrust sleeve 36a, and a seco d ball bearing assembly 34 is provided between the clutch member 32 and the bearing for the shaft 3|, these two bearing assemblies coacting to absorb the thrust of the spring 31 when the two clutch members are engaged, and thus provide for unrestricted rotation of the two shafts 24 and 3| under the influence of the motor 28. Similarly, a ball bearing assemblyfl36 is interposed between the thrust member 36a and the collar 35 to coact with the ball bearing assembly 3% in permitting free rotation of the shaft 24 under the influence of the retracting spring 39 when the two clutch members are disengaged.

. Declutching of the two clutch members 32 and 33 is eifected through operation of an electromagnet 43 having a plunger 42 which is adapted to thrust against the lower end of an arm 40 pivotally mounted by means of a pivot pin 4I upon a supporting member2'l which is carried by and projects laterally from the upstanding frame member 34a of the device. At its opposite end, this arm is bifurcated to embrace the collar 35, and the bifurcations carry opposed fingers entering the channel of this element to provide the required mechanical connection between the parts 35 and 40. As explained below, the solenoid 43 is arranged for intermittent.energization under the control of the contacts 80 at the rate of one energizing pulse'for each predetermined increment of drilling movement of the drill bit I2.

For the purpose of indicating the. off-normal settings which are imparted to the element 23 through operation of the above-described facilities, indicating means are provided which comprise a rotatable shaft 44 having. mounted for rotation therewith an indicating pointer 50 which, as shown in Fig. 9 of the drawings, may be cooperable with a scale 5| to identify the angular setting thereof. If electrical means are to be employed in indicating the drilling rate as represented by the angular setting of the shaft 44, this shaft may also be utilized to control the setting of an adjustable potentiometer 41 mounted upon the frame member 34c and having a wiper arm 41a rotatable with the shaft 44 in sliding engagement with a resistor element 412). This potentiometer may'be used to control the indication of a measuring instrument 49 having its scale appropriately graduated to indicate the drilling rate. connection is provided between the shaft 44 and the element 23 for the purpose of causing this shaft to follow movement of the element 23 away from its normal setting. This connection comprises a reel or drum v45 fixedly connected to the shaft 44 adjacent the element 23 and provided with an eccentrically mounted pin 46 which is engageable with the element 23.

I In order to rotate the shaft 44 in the reverse direction when the increments of movement of the element 23 away from its normal setting are decreased, reverse driving means are provided which comprise a torque motor 52 supported by the frame member 34c. This motor is arranged for intermittent energization under the control of the pulsing contacts 30 which are connected to the motor 52 through conductor I22 as mentioned above and is provided with a pulley 53 A one-way lost-motion driving.

fixedly connected to its rotor shaft and connected by means of a'string-54 to the pulley 45. One or two turns of this strips are wrapped around each pulley and-the respective ends thereof are fixedly attached to the two pulleys. Current for energizing-the various described circuit components ofthe apparatus shown in Figs. 1 and 2 of the drawings is supplied by a current source II4 ofappropriate voltage through a master switch II5. g

' In considering the operation of the described apparatus, and particularly the depth and 01T- bottom indicating facilities shown in Fig. 1 of the drawings, it will be understood that before a drilling operation is initiated, the registers and 66 are actuatedto their respective zero settings, i. e. to settings in whlchall order wheels thereof display a zero indication. Coincident with initiation of the drilling operation, the master switch II5 is closed to energize the motor 28 in the manner described below and to prepare circuits for the other circuit components of the apparatus. Asthe drilling operation is started and the drill string II moves downwardly in the well, the traveling block I5 is correspondingly lowered to rotate the pulley 60 through following movement of I the measuring line I! with the traveling block. As a result, the shaft 68 is rotated in a counter-clockwise direction as viewed from the lower end thereof to drive the ring.gear 96 in a clockwise direction as viewed from the left side thereof. Such rotation of the ring gear serves to' rotate the differential yoke and the orbital gears IOI and I02.in a corresponding direction, thus tending-to rotate the two shafts .59. and 10 in the same direction through the meshing engagement of the orbital gears with the gears I03 and I04. The torque thus transmitted to the shaft 10 tends to rotate the order wheels from their respective zero settings to theirrespective 9 settings, such rotation beingprevented through engagement of the pin IIO with the arm I01 and the edge of the housing aperture through which the pin IIO extends. The resulting movement of the arm I01 serves to hold the switch I05 in a setting wherein the contacts II2 are closed and the contacts II3 are open. Since the shaft 'DiiS thus locked against rotation in the direction dictated by'the direction of rotation of the shaft 58, the orbital gears IOI and I02 are rotated around the bevel 'gear I04 and function to rotate the shaft 69 in a counter-clockwise direction as viewed from the right end thereof. Such rotation of the shaft 53 functions to produce additive rotation of theorder wheel actuating shaft embodied in the well depth register 65. the drive ratiobetween the shaft GI and the shaft 69, the register 65 may be controlled in the manner just described accurately to indicate the depth of the well I0 as the drilling string II is advanced downwardly. Thus, this ratio should be such that the shaft 69 is rotated through exactly one revolution in response to each foot of downward movement of the travelling block I5, representing a one foot increase in the depth of the well I0.

The drilling and depth registering operation continues in the described manner unti1 the well has been drilled to a depth substantially equalling the length of the'Kelly Ila which is usually of the order of 40 feet. Since, however, depth measurement is normally started when the lower end of the dril1 bit I2 begins to descend below the top of the rotary table 9, the total depth registered By appropriate selection of after the full length of the Kelly has been drilled will be equal to the length of the Kelly. plusthewell. To perform this operation the drill string mustbe drawn upward'out of the well until the lower end of the Kelly I la is above the rotary table' 8. This requires that the bit he lifted of!- bottom a distance somewhatgreater than the length of the Kelly in order that the upper end of the drill collar and bit may be seized by the usual slips and held while the Kelly is being ,unscrewed. Thus the total reverse movement of the drill string may beassumed to approximate 50 feet. During such reverse movement of the drill string and the travelling block IS, the differential drive shaft 88 is reversely rotated, i. e. is driven in a direction opposite that required to produce additive operation of the depth register G5. Immediately this reverse rotation of the shaft 88 is started, the force holding the pin H against the arm 50! is relieved, permitting the switch I to shift its setting in the manner explained above. Incident to this switch operation, the contacts I I2 are opened to deenergize the motor 28 and the contacts H3 are closed to complete an obvious circuit for energizing the locking magnet 92. In operating, this magnet attracts the latching arm 9| into engagement with the gear 84, thereby to lock the shaft 69 against further rotation. With the shaft 68 rotating in a clockwise direction as viewed from the lower end thereof, and the shaft 89 held against rotation, the shaft 10 isrotated to produce additive actuation of the register 66, whereby the upward movement of the drill string and more particularly the distance between the end of the drill bit and the bottom of the well is registered upon the register 66. Obviously the same drive ratio obtains between the shaft Bi and the shaft 10 as obtains between the shafts BI and 69, so that the off-bottom movement of the drill string is accurately indicated by the register 66. Accordingly, after the drill string has been elevated the required 50 feet, this footage will be indicated by the register 66. Further, this indication is obtained while holding the depth indication of 60 feet previously set up on the register 65.

In order to add the new joint drill pipe, the Kelly Ila must be unscrewed from the bit stem and set aside while the travelling block i5 and hook are employed to lift the new section of pipe into the proper position for making the required screw connection with the bit stem. The auxiliary movement thus required on the part of the travelling block incident to joining the joint of drill pipe to the drill stem is, of course, transmitted to the crown block pulley 6. It will be understood, therefore, that if the driving connection between the shafts ti and 68 is maintained during such auxiliary movement of the travelling block i5, it is manifested as a change in the footage total indicated by the oif-bottom register 66. Preferably, however, the driving connection between the shafts 6i and 68 is broken at the time the drill stem is slip connected to the rotary table 9, thereby to prevent operation of the off-bottom footage counter 66 in response to the described auxiliary movement of the traveling block ii. To this end, the switch 93 may be closed to complete an obvious circuit for energizing the clutch magnet 82. In attracting the armature end of the arm lie, the magnet 82 relieves the bias exerted by the spring 11 upon the clutch plate 12 and thus breaks the driving oonnectionbetween the shafts. 6| and 68.

When the new joint of drill pipe, assumed to be of the same length as the Kelly I la, 1. e. 40 feet.

is joined to the drill stem to extend above the floor of the derrick, the travelling block l5 will necessarily have been returned to the position which it occupied at the end of the'drlll string lifting operation, i. e., a position 50 feet above the top of the rotary table 9, which distance is registered on'the 'oif-bottom footage register 66. The next operation is that of replacing the Kelly at the top of the drill string. This requires lowering of the travelling block and drill string, now including the new joint of pipe, into the well until only the upper end of the drill pipe projects above the rotary table 9. It may be assumed that 40 feet of downward movement of the drill string are required for this purpose. Before such downward movement of the drill string is started, the switch 93 is opened to deenergize the magnet 82 and thus reestablish the driving connection between the shafts BI and 68. Accordingly, as the drill string is lowered into the well, the register actuating shaft 10 is reversely rotated to subtract '40 feet from its total. In this regard it will be understood that since no torque is transmitted through the fourth order wheel Iii of the register, the microswitch I05 retains it normal setting to maintain the magnet 92 energized. At the end of the 40 feet of downward movement of the drill string, the register 66 will, therefore, ob-' viously have a reading of 10 feet indicating that the end of the drill bit is 1.0 feet above the bottom of the well.

With the drill string in this position, the switch 93 is again actuated to energize the magnet 82 and thus break the driving connection between the shafts 6i and 68. Following this operation, the travelling block 55 may be disconnected from the drill string and utilized to move the Kelly to a position wherein the required screw connection may be made between the lower end thereof and the upper end of the drill pipe joint. When this operation is completed, the travelling block is, of course, in a position 50 feet above the top of the rotary table 9, but since the driving connection between the shafts BI and 68 was broken during such elevation of the travelling bloek, the register 66 still accurately indi cates the actual distance between the drill bit and the bottom of the well. Following the described operation, the switch 93 may be again opened to deenergize the magnet 82 and thus reestablish the driving connection between the shafts ti and 58. The travelling block i5 may now be operated to lower the drill string further into the well until the drill bit engages the bottom of the hole. During such final downward movement of the drill string, the footage indicated by the register 66 is gradually reduced to zero, thus providing a positive indication which prevents the driller from too rapidly bringing the drill bit into contact with the bottom of the hole.

Coincident with engagement of the drill bit with the well bottom, all order wheels of the register t6 pass through their zero settings to ward their 9 setting, thereby to actuate the microswitch 805 in the manner explained above. Incident to such operation of the switch )5, the contacts H2 are opened to deenergize the locking magnet 32 and thus free the depth indicating register 65 for further'operation. Also. incident to such switch operation, the contacts 3 are closed to reestablish the circuit for energizing the motor 23. Following these switching operations, the pin engages the edge of the aperture through the housing of the register 66 and thus locks the shaft against further rotation. Accordingly, continued downward movement of the drill string ll produced through continuance of the drilling operation results in a corresponding additive change in the total indicated by the depth register 65.

As will be evident from the foregoing explanation, the described operating steps are repeated as required during progressive deepening of the well necessitating furtherpipe joint additions to the drill string. From this explanation, it will be understood that by suitable mainpulation of the switch 93, auxiliary adjustment of the offbottom footage register 66 to change the total indicated thereby is not required incident to the addition of each drill pipe joint. It may be desirable, however. particularly invthe drilling of deep wells, to alter the indication of the offbottom footage register 66 by predetermined increments, depending upon the depth of the well, in order to compensate for stretch" in the drill string. This may be accomplished on an empirical basis, predicated upon knowledge of the stretch characteristics of the drill pipe, by appropriate manipulation of the-vernier disc 31 to drive the register actuating shaft III in the proper direction to subtract from the indicated total the empirically determined footage representing stretch in the drill string. This vernier disc may also be conveniently employed to normalize either of the two registers 65 and 68 at any desired time. Preferably this is accomplished by first actuating the register 65 to zeroize the order wheel indications thereof during a period when the switch H5 is closed, and by then reversely rotating the plate to zeroize the order wheel indication of the register 65, all with the clutch plates 12 and 13 disengeged. During such reverse rotation of the plate 91 it is, of course, necessary to hold the shaft 10 against rotation in order that the rotary movement may be transmitted to the actuating shaft of the register 65.

The vernier disc 31 also operates in conjunction with the stationary pointer 39 to provide fractional footage indications. Thus this disc is driven through the meshing gears 94, 96 and 95 at the same rate of speed as the shaft 68. Moreover, a predetermined drive ratio exists between the speed of rotation of the disc 91 and the speed of rotation of either of the two shafts 63 and I0. I Accordingly, by appropriate graduation of the scale indicia provided around the periphery of the plate 31, this scale may be made to coact with the pointer 33 in providing a fractional footage indication which, in conjunction with the register 65, indicates the depth of the well to a fraction of a foot during downward progress of the drill string, and in conjunction with the register 88, provides a fractional footage indication of the position of the drill string relative to the bottom of the well As will be apparent from the preceding explanation, during each period when drilling is in progress and the register 65 is being operated to add to its depth total, the pulsing cams 81 and 88 are rotated, through the driving connection afforded by the meshing gears 83 and 34 and the shaft 35, to open and close the con- 7 l2 tacts 39 and 90, respectively, and thus generate two trains of current pulses which are utilized to control the drilling rate indicating facilities illustrated in Fig. 2 of the drawings. It will also be understood that the rate of such current pulse generation is determined in exact accordance with the rate of downward progress of the drill string during the drilling operation. Further, generationof the pulses is arrested concurrently with operation of the magnet 82 to arrest operation of the depth indicatingregister 65 at the end of a drilling operation. energizing current for the motor 28 and control pulses are only delivered to the drilling rate indicating apparatus during those periods when drilling is actually in progress.

With the motor 28 in operation, the element 23 is driven away from its normal settingthrough the driving connection afforded by the gear train, not shown. the shafts 3| and 24, and the engaged clutch members 32 and 33. Since the motor 28 is a constant speed device, movement of the element 23 away from its normal setting proceeds at a constant rate of speed. As the element 23 is rotated away from its normal setting, it correspondingly rotates the shaft 44 through the driving connection afforded by the pulley 45 and the pin 46. In other words, the shaft 44 and the indicating elements carried thereby follow the movement of the element 23 away from its normal setting. Such rotation of the shaft 44 and the pulley 45 also results in rotation of the torque motor rotor through the connection provided by the string 54.

With drilling in progress, the cam 88 intermittently closes the contacts in the manner just explained. Each time these contacts are closed to indicate the deepening of the 'well In by a predetermined amount, an obvious circuit is completed through these contacts for energizing the torque motor 52 from the current source 4. During the initial operation of the apparatus such energization of the motor 52 is without effect since the pin 46 is directly engaged with the element 23. Immediately the contacts are opened, the torque motor 52 is deenergized. When thereafter the contacts 89 are closed by the cam 31, an obvious circuit is completed through these contacts for energizing the magnet 43 from the source I [4. In operating, this magnet attracts its plunger 42 into engagement'with the lower end of the arm 40, thereby to move the declutching collar 35, the shaft 24 and the clutch member 33 slightly to the right and thus disengage the clutch member 33 from the clutch member 32. When thus released from the driving force of the motor 28, the shaft 24 and the parts carried thereby are returned to normal under the influence of the spring 39,which spring is obviously tensioned during movement of the element 23 away from its normal setting. Thus, the element 23 is restored to normal and the shaft 44 is left standing in the position to which it was actuated during movement of the element 23 away from its normal setting. During continued rotation of the cam 81, the contacts 33 are opened to deenergize the magnet 43 and thus permit reengagement of the clutch members 32 and 33 under the influence of the spring 31. Incident to re-engagement of the clutch members 33 and 32, the motor 28 is again rendered operative to drive the element 23 away from its normal setting. The increment of 4 movement which occurs during the Thus I the element 23.

interval between the delivery of successive current pulses to the magnet 43 is, of course, de-

. termined by the rate of penetration or down- I ward movement of the drill bit I2, 1. e. the

drilling rate. If the drilling is decreasing, the

interval between the last described pulse devbe moved a greater increment away from its normal setting during the timing interval under consideration than the increment of movement which occurred during the preceding timing interval. In moving beyond its previous oifnormal setting, the element 23 further advances the shaft 44 and the indicating elements 50 and 41a carried thereby away from their respective normal settings. Hence during the next succeeding current pulse interval, in response to which current is again delivered to the torque motor 52 and the release magnet 43 in the order named, the torque motor is still ineffective to rotate the shaft 44 back toward its normal setting. Energization of the release magnet 43 results in normalizing of the element 23 in the exact manner explained above.

From the preceding explanation, it will be understood that. so long as the drilling rate decreases to decrease the rate of pulse generation of the cams 81 and 89, the increments of movement of the element 23 away from its normal setting which occur between successive operations of the magnet 43 are progressively increased to progressively move the shaft 44 and the indicating elements controlled thereby farther away from their respective normal settings. When the drilling rate becomes constant, the increments of movement of the element 23 away from the normal setting of this element become equal. In this case also, the momentary energization of the torque motor 52 which occurs at the end of each timing interval is likewise without effect to produce movement of the shaft 44. Thus, the indicating elements 41a and 50 are held in settings representative of the constant drilling rate.

When, on the other hand, the drilling rate increases, the periods separating the delivery of current pulses to the magnet 43 become correspondingly shorter. As a result, the increments of movement of the element 23 away from its normal setting are correspondingly decreased, so that in each instance the element 23 stops short of engagement with the pin 46. In such case the momentary energization of the torque motor 52 which occurs at the end of each timing interval results in rotation of the shaft 44 back toward its normalsetting by the driving force exerted thereon through the pulley 53, the string 54 and the pulley 45. In this regard it is noted that regardless of the setting of the element 23 relative to the pin 46 at the time the torque motor 52 is energized, this motor is only capable of developing sufficient torque during its short period of energization to move the shaft 44 a small increment back toward its normal setting. Thus, it will be understood that if a large increase in the drilling rate occurs and is sustained, several timing intervals will elapse before the torque motor 52 fully returns the shaft 44 to a setting representative of the actual drilling rate, i e. a setting wherein the pin 46 is engaged with The purpose of this arrangement is to prevent the shaft 44 and the indicating elements carried thereby from following transient increases in the drilling rate which may 14 not be truly representative of a sustained increase in this rate.

From the above explanation, it willbe apparent that the shaft 44 is controlled rapidly to follow any decrease in the drilling rate but only slowly to follow an increase in the rate. It will also be understood that the indicating element 50 assumes a setting relative to the scale 5| which is indicative of the drilling rate. Preferably this scale is suitably'graduated to indicate the drilling rate directly in feet per hour. Similarly, the wiper arm.41a is variably positioned along the resistor 41b inaccordance with the drilling rate. This wiper, when adiustably positioned along the resistor 41b, impresses a variable portion of the voltage of the source H4 across the terminalsof the indicating instrument 49, this voltage increment increasing with a decrease in the drilling rate and vice versa. Thus, by suitable graduation of the instrument scale, the instrument 43 may be controlled directly to indicate the drilling rate in feet per hour.

While there has been described what is at present considered to be the preferred embodiment of the invention, it will be understood that various modifications may be made therein which are within the true spirit and scope of the invention as defined in the appended claims.

I We claim:

1. Apparatus for indicating the rate of drilling a well, the depth of the well and the position of the drill string relative to the bottom of the a well; comprising depth indicating means responsive to downward progress of the drill string into the well for cumulatively indicating the depth of the we1l,a magnet adapted when energized to lock said depth indicating means against operation, drilling rate indicating means including an indicating element and motor means for moving said element to a position indicative of the rate of downward progress of the drill string, drill string position indicating means responsive to upward movement of the drill string to indicate the position of the drill string relative to the bottom of the well, and switching means controlled by said position indicating means to energize said motor means so long as drilling is in progress and to deenergize said motor and energize said magnet when said string is moved to a position off the bottom of the well.

2. Apparatus for indicating the rate of drilling a well, the depth of the well and the position of the drill string relative to the bottom of the well; comprising depth indicating means responsive to downward progress of the drill string int the well for cumulatively indicating the depth of the well, pulse generating means responsive to the operation of said depth indicating means for generating current pulses at the same rate, means for varying said rate of current pulse generation in response to the rate of downward progress of the drill string, a magnet adapted when energized to lock said depth indicating means against op-v eration and to arrest the generation of said pulses, drilling rate indicating means including l switching means controlled by said position indicating means to energize said motor means so long as drilling is in progress and to deenergize said motor and energize said magnet when said string is moved to a position oi! the bottom of the well.

3. Apparatus for indicating the rate of progress of a drill string into a well during a well drilling means responsive to movement of the drill string into the Well for intermittently energizing said release magnet at intervals varying in accordance with variations in the rate of progress of the string into the well, whereby variations in the increments of movement of said element away from said normal setting are produced in response to variations in the rate of progress of the drill string into the well, an indicating element directly actuated by said first-named element to indicate any increase in the increment of said first-named element away from said normal setting, motor means for causing said indicating element to follow any decrease in the increments of movement of said first-named element away from said normal setting, and means responsive to movement 01 the drill string into the well for energizing and then deenergizing said motor means just prior to energization of said magnet.

4. Apparatus for indicating the rate of progress of a drill string into a well during a well driiling operation. comprising an electromasnet, a motor, pulse generating apparatus including means for alternately transmitting non-overlapping pulses to said motor and said electromagnet; each pulse delivered to said motor being completed before the next succeeding pulse is delivered to said electromagnet, means responsive to changes in the rate of movement of the drill string into the well for correspondingly varying the rate of generation of said pulses by said pulse generatin means, an indicating element for indicating variations in the rate of movement of the drill string into the well, said indicating element having a normal setting, means in part controlled by operation of said electromagnet for adiustably moving said indicating element away from said normal setting, and means responsive to operation of said motor for returning said indicating element toward said normal setting.

JAMES W. PITCHER. JOHN T. CAILAHAN. JR.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED, STATES PATENTS Number Name Date 1,835,804 Morra Dec. 8, 1931 2,295,787 Hirth Sept. 15, 1942 2,322,478 Scherbatskoy June 22, 1943 2,326,219 Hayward Aug. 10, 1943 2,365,014 Silverman et al. Dec. 12, 1944 FOREIGN PATENTS Number Country Date 348,832 Great Britain May 21, 1931 

